test: add integration test for declining an invite to an empty room

[paul8711-code]

This PR is related to #4642. I have added the first of two integration tests (as requested), according to which declining an invite worked just fine.

• I've documented the public API changes in the appropriate changelog files (see Writing changelog entries).
• This PR was made with the help of AI.

Signed-off-by: Paul8711 154304377+paul8711-code@users.noreply.github.com

[paul8711-code]

@Hywan could you take a look at this PR when you have time? It is directly relevant to our discussion in the previously mentioned issue.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.90%. Comparing base (340bbc8) to head (f6829ad).
⚠️ Report is 14 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6686   +/-   ##
=======================================
  Coverage   89.89%   89.90%           
=======================================
  Files         396      396           
  Lines      110264   110264           
  Branches   110264   110264           
=======================================
+ Hits        99117    99128   +11     
+ Misses       7376     7375    -1     
+ Partials     3771     3761   -10     

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[codspeed-hq]

Merging this PR will not alter performance

✅ 50 untouched benchmarks

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_{Comparing paul8711-code:test/empty-room-invite-decline-test (f6829ad) with main (567463d)}

[Hywan]

Thanks for the test! I think we need to tweak it though, as it contains a flow right now.